The invention relates to bypass turbojet engines such as are used for military aircraft and which have an afterburn or reheat chamber which acts as a second combustion chamber.
This second combustion chamber enables a second injection of heat to be made into the combustion gases between the time when they issue from the turbine stages of the engine and the time when they are ejected from the exhaust nozzle. This help to increase the gas ejection velocity and increase engine thrust. The gases from the secondary (or bypass) flow serve to cool the afterburn chamber and supply unburnt oxidant thereto.
Afterburn systems comprise fuel injectors and devices known as flame arresters which take the form, for example, of radial arms. These arms serve to stabilise the flame in the gas flow leaving the gas generator, the flame being arrested by the creation of an air recirculation zone using a turbulence-generating obstacle.
The flame arrester arms are essential for afterburn or reheat operation, but are useless and even detrimental during non-afterburn or "dry" operation since they cause energy losses and reduce engine efficiency.